SMM (System Management Mode) is an essential part in central processing units, such as 32 or 64-bit Intel (microprocessor. Many important computer platform activities are generally performed in SMM code provided by original equipment manufacturer (OEM) firmware on a computer platform, such as enabling and disabling an Advanced Configuration and Power Interface (ACPI), utilizing a digital thermal sensor, the hot-plugging of memory, etc. A core will enter SMM if it receives a SMI (System Management Interrupt).
The central processors residing in current computer platforms frequently have several cores (i.e. 2, 4, 8, 16, etc. cores per processor). Although the performance of a many-core central processor can generally outperform their single-core counterparts, there are several technical challenges to efficiently operating in a many-core environment. Currently, platform firmware synchronizes all CPU cores for SMM in order to meet Operating System (OS) software models because the OS kernels cannot tolerate one core disappearing or not responding to actions like an Inter-Processor-Interrupt (IPI).
The PI (Platform Initialization) 1.1 (www.uefi.org) specification defines SMM architecture for Unified Extensible Firmware Interface (UEFI)-based firmware. However, both current UEFI firmware and legacy basic input/output system (BIOS) disable interrupts in the SMM environment.